1. Field of the Invention
The subject invention relates to fluid filtration devices, and more particularly, to a lenticular filter cartridge assembly housed within a disposable capsule and intended for use in conjunction with a fluid processing system.
2. Background of the Related Art
Cell type filter assemblies, often referred to as lenticular filter assemblies, are well known in the art and have been employed in fluid processing systems for many years. An early example is disclosed in U.S. Pat. No. 2,788,901 to Boeddinghaus et al. Lenticular filter assemblies often include a plurality of vertically oriented coaxially arranged filtration cells disposed within a cylindrical housing. Typically, such a filter housing is formed by structural portions which are secured together by conventional clamping devices that allow for access to the interior of the housing to facilitate filter replacement and maintenance. Examples of prior art filtration cells are disclosed in U.S. Pat. No. 4,783,262 to Ostreicher et al. and U.S. Pat. No. 4,347,208 to Southall
In known prior art lenticular filtration assemblies, the uppermost and lowermost filtration cells in a filter housing are oftentimes provided with a compressible gasket or O-ring to effect a seal against the housing. See, for example, commonly assigned U.S. Pat. No. 4,704,207 to Chu. In other devices, these cells may be welded to the top and bottom of the cartridge housing to seal process fluids within the system. Additionally,it is known to provide sealing gaskets intermediate adjacent filtration cell layers to effect a seal therebetween, as disclosed in U.S. Pat. No. 4,704,207 to Chu.
During use, process fluid enters the filter housing through an inlet port, passes through the filtration cells, and exits the housing through an outlet port. Over time, the filtration cells will exhibit plugging or the batch will be completed, and the filtration cells are not reused to prevent cross-contamination of process fluids. Thus, to properly maintain the fluid processing system, the structural portions of a conventional filter housing must be separated, the spent filtration cells must be removed, the housing must be thoroughly cleaned to remove contaminants and residues deposited therein, and new filtration cells must be emplaced in the housing, along with any associated sealing gaskets. Such a maintenance procedure can be time consuming and costly since the fluid processing system must be brought off-line for an excessive time period. Thus, it would be extremely desirable to provide an inexpensive fully encapsulated cell type filter assembly that could be readily removed from a fluid processing system, discarded after removal, and replaced with a new filter assembly.
Another problem associated with the use of conventional inline filtration systems such as a lenticular filtration systems is that of hold-up volume. This is the volume of excess process fluid which accumulates in the bottom of the filter housing below the outlet opening thereof. During routine maintenance, or when spent filtration cells are replaced, the filter housing must be opened. This can result in contamination of the excess process fluid which must then be discarded. In filtration systems employed in the manufacture of biopharmaceuticals or pharmaceuticals, process fluids can be extremely valuable, and the loss thereof due to contamination can be very costly. A prior art filter assembly which employs a mechanism for reducing or decreasing hold-up volume in a filter housing is disclosed in U.S. Pat. No. 5,462,675 to Hopkins et al. This prior art assembly does not however, provide a mechanism for recovering excess process fluids from a filter housing. Clearly, the provision of such a mechanism would be extremely desirable.